A big Citroen will be comfortable. Or a Japanese luxobarge, from Lexus to Nissan QX. Most fast European machines will be involving but not comfortable - Audi quattro for example may be a bit stiff for long distances. Matter of taste of course.

The most comfortable I have ever driven was a 25 year old Silver Shadow. A Rover P5 or P5B runs it a close second. The main problem would be petrol costs as you would need 3 to 4 gallons a day. Another incredibly comfortable car was an old Renault 16. All will leave you unstressed providing you don't try and find their low'ish cornering limits!

Did a nightmare journey from Leeds to Haslemere in '77ish trying to find a way not to use a fog-bound M1. 6 hours behind the wheel of a Renault 16TX and prickly eyes the only symptom of tiredness.

Used to commute 140 miles a day in, variously, a Citroen Visa GT, a Citroen BX 16v and a Citroen XM; that's a good test of comfort. The XM was easily the best. Slightly OT, despite having 50 fewer bhp than the BX and being heavier, my journey times were better in the XM. Never did work that one out. I also rate the Rover P6 and Citroens DS and CX for comfort.
Hawkeye
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Stranger in a strange land

Try driving a Smart. I know it is not everyones cup of tea, but it is the most comfortable car to drive.
Dont knock it until you try it.
It is the only car that i dont fall asleep or feel drowsy in, whilst driving.
but when driven i can be off within a couple of mls

From recent experience, I could recommend a Skoda Superb - try to get the Comfort(!) model with 130pd diesel, it's got sensible 205x55x16
wheels, all nicely adjustable seat/steering wheel (no lumbar support adj. IIRC, though) & cruise control, Cd changer - the suspension is so supple you can actaully push down the rear end by hand!

For me at least, good lumbar support is the crucial thing to avoid back pain -also a good driving position so that you don't have to be too close to the steering wheel to depress the clutch.

Adjustment of the backrest and lumbar support by wheels rather than levers is a big advantage - VWs, Audis, Skodas and (I think) SEATs have this; not sure about Volvos and Saabs but most testers find that their seats are uniformly good.

Don't go for too downmarket a specification as you may not get adjustable lumbar support. You'd think that would be a fairly basic standard requirement, wouldn't you - but marketing men always seem to know best.

Many French cars feel nice and soft and comfortable when you first sit in them, but don't always offer enough support on a long journey.

I don't mean to be so vulgar as to blow the trumpet of a car I own, but the Scenic is excellent in terms of comfort. Good seats, nice driving position, low noise levels, and a light, airy interior. Makes 200 miles feel like 20.

C5 definitely has the best suspension of any car on sale for comfort over normal roads. I find the seats are fine too - I can drive from Perpignan to Calais in 10 hours stopping twice, without feeling any aches or numbness. In a C class my rump goes numb after 2 hours and have to stop to walk around for the feeling to return.

The most comfortable car I have ever driven is the Audi A8 I recently drove.Near silent cruising,great ride on the air suspension.Very comfy seats,great sound system and an excellent ergonomic interior.Found it to be better than all the mercs and BMW's I have driven(i have yet to drive the s-class)and I prefer the image to boot.

Most comfortable car I've been in was an old Montego, had excellent seats much like cozy armchairs - could've easily sat all day and not cared a jot. It had a very smooth ride too, believe it or not! Almera's seats are a bit less "cozy" but I've driven for 5 hours non-stop without backache. Among the worst were a Vauxhall Vectra B (1999 model), and a Renault Clio 2003 model. The Clio I once drove on a 50-mile round trip to the airport and felt every inch of the road for days after - not good for just over an hour of driving.

It's funny, but driving the C-Max you wouldn't think it's a very comfortable car, but it is. The ride isn't especially quiet or smooth, but there's something about the seat and driving position that makes it very comfortable to drive. On my old cars I tended to have to shift around in the seat to get comfortable after driving for a while, but I drove around 1500 miles on holiday recently and even on long stretches of driving I got out of the car afterwards not feeling stiff or uncomfortable at all.

Agree about the C-Max - excellent seat despite (on the one I tried) not having adjustable lumbar support. What put me off was not having anywhere to put one's left foot when not on the clutch. This is quite a common Ford failing, and it's spread to the Volvo V50.

As has previously been pointed out there are many definitions of comfort. Soft and squishy or firm and supportive.

Most Volvo's have excellent seats, truly supportive, very adjustable but from my experience this adjustment is not required once set to your liking.

I drive some very long journeys from nr. Eastbourne to North Wales, Devon & Cornwall (and back in the same day in most cases), and occasionally to the Highlands of Scotland which can be a 14 hour jaunt with just a stop for fuel. Even Zirch from home in a day has been done a few times along with day-long trips to southern Germany.

I arrive feeling very good. Certainly I used to suffer from significant back problems when I drove other cars and it is only since my 2 yeards with my S60 that I have not had any significant back pain associated with driving.

However, the ride is pretty firm and unforgiving, even on 16" wheels and there are the occasional yelps from me when driving over the odd pot hole or two.

When it comes to the soft and squishy route all old Citroens fit the bill. My GSA (anyone under about 35 won't know what I mean) was like a luxury liner with a soft as soft ride that soaked up every bump with it's oleo pnuematic suspension. Shame the rest of the car self destructed.....

After driving for two or so hours I feel as fresh as a daisy and ready for more.

Also, it's a very quiet car (at least on the base 16" wheels) which means you can listen to the radio or music properly.

If you go down the C5 route, do try it first. I had one as a hire car and, although the ride was truly fabulous, the seats gave insufficient lateral support for my taste and the chassis gave no feedback at all.

Re-reading the OP's question, I think it says he's looking for a car that doesn't feel uncomfortable after 33 miles. ('66 miles a day' meaning two journeys of 33, presumably with a day's work in between.) That's only an hour or so at most and, if so, there ought to be mountain of choice, and it really shouldn't be necessary to pay the price of a Volvo or Saab to arrive without aches and pains.

Trouble is, there really is no Most Comfortable Car, any more than there are Most Comfortable Trousers (whatever you might read in the back pages of Telegraph Weekend!) It has to be a comfortable match between car and driver. I like Saabs and Volvos because they give me enough space and support for my long, broad-shouldered frame, with enough length in the seat cushions to support my thighs, and enough room round the pedals for my size 12 feet in whatever shoes I happen to be wearing. Some of these same factors might make the car positively uncomfortable for a smaller driver.
On the other hand, I've driven a C5 and loved the wafty ride, but found the seat OK at best, the steering wheel too far away and the pedals too close together for my liking. I can see what people like about it - and it looks great in bright metallic red - but I don't think it's for me.

I've driven a rented Focus over similar distances and got out feeling fine. It's what I'd probably buy in the OP's position.

Most comfortable car I ever experienced was a Renault 20. In fact, when it was written off, I kept the passenger seat and mounted it on timber bearers and put it in the corner of the garage. Perfect place to sit during tea breaks on my weekends of spannering and welding :-)

Which Clio do you have I find the seats in the wife's Clio very comfortable.

My dad seems to think so (he has a '99 1.6 auto Clio).

I find it far too cramped to ever get comfortable. It may be a quirk with this particular car, but I find that the seat won't go far enough back, and I'm touching the hard plastic in all directions.

Comfort is about a lot more than ride and seat quality -- the positioning of the wheel, gearstick, pedals etc are just as important. On the Vectra I get a pain in my left side, with the Astra a shooting pain down the right leg, with the Accent cramp in the left.

From a personal perspective the car I've found to be the most comfortable is the 99-02 Primera. Everything is in the right place (for me), the seat is a good compromise between softness and support and generally I can drive for hundreds of miles without coming out the other end with pains everywhere.

Your results may vary -- you need to drive the cars a fair distance yourself, and not go on the experiences of others which are an irrelevance unless you're both the same size and shape.

I ave a Volvo V70 T5. Bought at 3 years old 52-reg with 160K miles (ex Police car, with full service history). I travel 20K a year nowadays. Rush hour commutes, local B-roads, motorway miles, all leave me unstressed and wit no aches.
Seats are extremely comfortable and the powerful engine makes it an extremely relaxing car to drive. Pulls up ills with ease, and will cruise at 120mph (in Gremany) all day.
Only complaint is that the steering whell is only adjustable for rake, not reach.

The best seats I've ever put a bum on were:
HA Viva van (less than half an inch of padding)
Maxi (upright, bar stool with flat steering wheel)
I could get out of both after a couple of hours without feeling a twinge.

I have a Renault Clio 1.2 Authentique (the most basic). It is very cheap to run but, understandably, lack the refinement of a larger car.

The common theme in the replies seems to be that big Swedish, Japanese and Germans cars are most comfortable and reliable. My Citroen C5 suggestion may not be best. While they benefit from hydromatic suspension and being cheap to buy second hand, they are not "drivers" cars or the most reliable.

I have also thought about Mk2 Mondeos. A car designed for reps doing 50/60k a year. I guess that they would have to be comfortable to compete in that kind of fleet car market.

An Audi A6 was one suggestion. A diesel for £5k would have intergalactic mileage. That does not necessarily deter me. I had a Golf with 200k+ mile when I sold it. If an A6 could run to 300k+ without serious expense and the hassle of repairs, it might be an option.

>Only complaint is that the [V70] steering wheel is only adjustable for rake, not reach.

You sure about that, Cab-maker? If it's the 2000-2007 V70 (as a 52 plate implies) I'd expect it to have the same wheel adjustment as my 52 S60, which pulls out plenty far enough even for me.

I agree about the engine's contribution, though: a good, torquey one makes long trips much more relaxing, since you can always get back to cruising speed as soon as the opportunity presents itself. To return to the C5 for a moment, I tried both 1.8 petrol and 2.0 diesel versions on the same day over the same route, and the diesel's torque makes it a vastly superior machine.

Try a Rover 75. Forget all the fuss about the styling and reliability etc. When it comes down to it, they're cheap, as reliable as most other cars, have a great ride, lovely interior, and most reviews say that they're as relaxing as a jag. Get one with the BMW diesel for maximum relaxed driving style.